Method for imparting finish to cotton yarn



Aug. 11, 1942. w. H. FURNESS METHOD FOR IMPARTING FINISH T0 COTTON YARNFiled Aug. 1 2, 1939' INVENTOR igaffiua, 2

lilllllllllllllllll- ATTORNEYS v Patented Aug 11, 1942 UNITED STATESPATENT OFFICE-F METHOD FOR numa'rnvc Fmsn 130 COTTON YARN William H.Furness, River-ton, N. J., assignor to Americanllayon Company, Inc.,Riverton, N. 1., a corporation of New Jersey Application August 12,1939, Serial No. 289,i69

8 Claims. (01. 8-123) This invention relates to a method of andapparatus for finishing cotton yarns to impart thereto a luster andfinish like that of but superior to mercerization. The invention isuseful on plied yarns but may also be employed on single yarns.

The object of the invention is to provide a method and an apparatuswhereby cotton yams can be effectively and economically finished withone form of apparatus for carrying out the same are illustrated, Figure1 being a diagrammatic side elevation of the apparatus; Figure 2 being afragmentary top plan view of one unit of the apparatus, drawn on anenlarged scale; Figure 3 being a section taken on the line 3-3 of Figure2; and Figure 4 being an enlarged sectional detail of the inventionshowing how the yarn is led from the bath F to the bath G to be laterdescribed.

In the drawing I have shown a machine for simultaneously treating sevenends, but it is to be understood that the number of ends treated may bevaried, for which purpose the width of the apparatus may be increased orthe units multiplied.

The ends are drawn through the major portion of the apparatus by suchmeans as the squeeze rolls 7, the yarn being drawn off of cones 8carried by a creel 9, located at the forward end oi the apparatus. Theyarn first passes through a hot caustic soda bath A which, in theapparatus illustrated, is approximately fifteen inches in length with aspeed of draw such that any given portion of the yarn remains in thebath for about two seconds. Caustic soda solution is controllablysupplied through the pipe I!) from the combined heater and storage tankll. Overflow from the bath A goes to the filter l2 and is re-circulatedto the tank H by means of the pump l3 and pipe II. The caustic sodasolution is of mercerizing strength, preferably 300-350 grams per liter,and is kept at boiling temperature and preferably at at least. 105 C.because at that temperature it efiectivelywets the yarn and mercerizesit. The action of the hot caustic soda is at least twofold. It imparts ahigh luster to ders unnecessary, if desired, the use of high pricedwetting agents.

On leaving the bath A, the ends run through a hot water wash bath B, towhich hot water is delivered at a rate of about 45 cc. per minute, thewater flowing counter to the direction of the passage of. the yarn. Hereit is the intention to remove a portion of the caustic soda. Theoverflow from the bath B thus contains approximately '75 grams of NaOHper liter (on the basis of treating ten ends of 20s/1 yarn) and is sentback to the heating tank ll,helping to compensate for the-water lostfrom the caustic soda. solution for the bath A by boiling.

Bath B is likewise approximately fifteen inches in length, and it takesabout two seconds for the ends to pass therethrough.

The ends now pass through a second hot water wash bath C. Here again itis the intention likewise about fifteen inches in length, so that ittakes about two seconds for the. ends to pass therethrough. Thereduction of the caustic soda in successive steps is advantageous.

The ends now pass through a third water wash bath D where the washing isquite rapid, hot water being delivered thereto at the rate of about 165cc. per minute. This bath is intended] to remove any remaining causticsoda from the surface of the thread, leaving behind the caustic sodaembodied in the yarn. The concentration of the overflow is so small(about three grams per liter on the basis of ten ends of 20s/ 1 yarn)that recovery is impractical and the solution is discarded. Bath D islikewise counter-flow, and is about fifteen inches in length, andittakes about two seconds for the ends to pass therethrough.

The ends now travel through air between the bath D and the bath F. Thespace between the baths D and F is approximately fifteen inches.

During the passage through the air, the excess the finished yarn, evento single yam, and mm preferably not counter-flow, and the solution isgiven, there is a. slight excess of copper sulphate,

about two per cent. This excess is employed for the reason hereinafterto be pointed out. The solution as prepared thus comprises a coppersulphate-ammonium-caustic soda solution (probably in the form of atemporary compound) and the excess or copper sulphate which is presentas tetrammonium copper sulphate in solution having united with some ofthe excess ammonia.

When the process is in operation, the yarn entering the bath F carriesalong with it a certain amount of caustic soda. The excess of coppersulphate is suflicient to compensate for the caustic soda thusintroduced so that, in operation, the bath is a substantiallydynamically balanced one. At suitable intervals the bath is analyzed andsuflicient tetrammonium, copper sulphate and free ammonia are added tomaintain the proper concentration. It is unnecessary to add any causticsoda to the bath for the reason that caustic soda is being continuallybrought into the bath with the yarn. From about 25 to liters of thesolution is used and is circulated, entering the bath at the end atwhich the yarn enters. The overflow pipe H is located at the oppositeend of the bath and discharges into a. settling tank [5. From thesettling tank the solution is pumped back to the tank l6.

In order to prevent the ends from contacting with one another in passingthrough the bath P.

which would be objectionable as it would cause sticking and fiberbreakage, I provide individual channels for the ends. These channels areformed by a series 'of upright plates l1, providing channels open at thetop and the bottom.

' The channels'are capillary, i. e., the plates are spaced suflicientlyclose together that capillary action will carry the solution upwardlyabove the normal level of the solution in the bath, as shown in figure3. By this it is ensured that the ends, which enter just above thenormal level of the bath. will travel under the surface of the solutioninstead of upon the surface of the solution. This is of great importanceas thereby the ends are uniformly subjected to the action of thesolution.

The concentration of the solution is such that, for the time that theends take in traveling therethrough, the fibers projecting from theyarn'are dissolved, while the caustic soda inside the yarn prevents thesolution from penetrating too deeply and at the same time neutralizes 0rcompensates for the excess of copper ammonium sulphate in the solution.The body of the Yarn is not dissolved and the formation of a core ofregenerated cellulose is thus prevented, when the yarn reaches the acidbath G which succeeds the bath F. In this way, it is possible to producea yarn which is not stifi but is nevertheless freed from prjectingfibers or fuzz and which in consequence has an improved finish orappearance and also an improved feel or hand. The

yarn leaving the bath is thus composed ahnost entirely of alphacellulose, because the bath, in addition to removing the fuzz, in largepart relesser celluloses resulting from variations in the conditionsunder which growth occurred. In this connection it is also to beobserved that the yarn, as it leaves the bath F and enters the acid bathG, is free of any surface coating of dissolved cellulose. and consistsof practically nothing but alpha cellulose. possibly in a softenedcondition.

When single yarn is being processed, in order to ensure that there shallbe no coating of dissolved cellulose on the yarn as it leaves the bathF, I- may bend the plates II in ogee form at a plurality of points, asindicated at IS in Figure 2, so that the ends in traversing the bathwill rub gently against the plates, thus stripping or: any coating ofdissolved cellulose resulting from the dissolving of the fuzz. This doesnot impair the yarn because there will always be a slight film of liquidbetween the yarn and the rubbing surface. The fact that the solution isa relatively dilute one also assists in preventing any coating ofdissolved cellulose as, in a dilute solution, the dissolved cellulosehas a tendency to disperse or float away. That portion which remains insuspension and is carried into the overflow. settles out in the settingtank IS.

The acid bath is preferably in two boxes, the

I concentration in the first varying usually from uid with the threadleaving the bath F, I prefer to controllably supply acid solution to thebath of the above concentrations at the entrance ends of the boxes, withthe overflow at the exit'ends. Should there be an dissolved cellulose onthe ends entering the bath, it is regenerated and set, but loosens anddrops oil so that the yarn leaving the acid bath is free of any coatingof regenerated cellulose.

The ends now enter three counter-flow water washes, H, J, and K. Theoverflow from bath K enters bath J, and from bath J enters bath H. Theoverflow from bath H is discarded.

The ends now pass through the squeeze rolls 1 which are preferablyprovided with an overhead water spray to assist in removal of acidcarried by the yarn.

Then there is the final water wash L in which hot water is preferablyemployed, sufiicient water being used to ensure that the yarn shows noacid reaction to litmus as it enters the dryer M, which is preferably ofdrying can type, a novel and advantageous drying for my yarn. In passingthrough the drier, the yarn loses its moisture and dries, under thetension that is created between the squeeze rolls and the spools N. Fromthese spools the yarn is subsequently coned for shipment.

If the various baths be lengthened, it may be desirable to provideadditional squeeze rolls at one or more points. These should preferablybe synchronized so that the tension in the system,

copper oxide.

The overflow from the bath G may beevaporated in the evaporator l9 untilthe acid has "been restored to the desired strength. This acidcontaining the sulphates of copper, ammonium and sodium is returned tothe reservoir 20 repeatedly, until the salts crystallize on coolingafter evaporation. The salts areseparated from the liquor and dissolvedin water and the liquor returned to the bath as before. The excess acidpresent in the solution of dissolved salts, is neutralizer with causticsoda, and a calculated amount of solid caustic soda is added to thecooled solution to release the ammonia from the ammonium sulphate. Apart of the ammonia combines with the copper sulphate to form coppertetrammonium sulphate, and the rest remains in solution as free ammonia.This solution is then cooled while being stirred. The sodium sulphate asNazSO4.10H2O (Glaubers salt) separates in fine crystals and is removedin a hydro-extracton. Any copper solution adhering to the crystals maybe dissolved by removing them in hot water and filtering oil? theinsoluble The salt is then re-crystallized. This product is salable assuch or can be dissolved in water and by means of electric currentdecomposed into sodium hydroxide and sulphuric acid for selling and forre-use in the system. To the copper tetrammonium sulphate and am-- monlasolution which was separated by the first crystallization of sodiumsulphate, caustic soda is added to make the solution of theconcentrations indicated for the bath F.

The solution from the washes H, J and K is so dilute that only coppercan be recovered therefrom. By adjusting this solution to a pH of 5.7 bythe addition of caustic soda, the copper separates as basic sulphate andcan be dissolved and used in the preparation of the treating solution.

Referring to Figure 4, the end 30 of the tank of the bath F stands high,so that the yarn can freely enter into bath G and under a guide 3|, wellremoved from the entrance end of bath G.

This application is in part a continuation of my co-pending applicationSerial No. 105,476, filed October 14, 1936.

I claim:

1. The continuous process of treating and finished cotton yarn whichcomprises, drawing the yarn through a caustic soda bath of mercerizingstrength, then through several successive water baths to remove excesscaustic soda but leaving behind the combined caustic soda, then throughspace to permit drainage o1 excess liquid, when while still moistthrough a copper sulphate, ammonia, caustic soda solution prepared insubstantially the following proportions, coppersulphate 39.31 grams perliter, ammonia 66 grams per liter, caustic soda (NaOH) 12.105 grams perliter, and water to make one liter,

whereof the excess copper compensates for the caustic soda carried intosaid solution by the yarn then through an acid bath, then throughishinga multiplicity of separate cotton yarn ends .which comprisessimultaneously drawing the ends through a caustic soda bath ormercerizing strength, then through successive water baths to removeexcess caustic soda but leaving behind the combined caustic soda, thenwhile still moist through a copper sulphate, ammonia, causticsodasolution prepared in substantially the following proportions, coppersulphate 39.31 grams per liter, ammonia 66 grams per liter, caustic soda(NaOH) 12.105 grams per liter, and water to make one liter, whereof theexcess copper compensates for the caustic soda carried into saidsolution by the yarn, the ends being maintained out of contact with oneanother in the passage through said solution; then through an acid bathand through water baths to remove the soluble salts and the acid, dryingthe ends and winding the treated, dried ends on individual holders.

3. The continuous process or treating and finishing a multiplicity ofseparate cotton yarn ends which comprises simultaneously drawing theends through a caustic soda bath of mercerizing strength, then throughsuccessive water baths to remove excess-caustic soda but leaving behindthe combined caustic soda,- then while still moist through a coppersulphate, ammonia, caustic per liter, ammonia 66 grams per liter,caustic soda (NaOH) 12.105 grams per liter, andwater to make one liter,whereof the excess copper compensates for the caustic soda carried intosaid solution by the yarn, the ends being maintained outof contact withone another in the passage through said solution; then through an acidbath and through water baths to remove the soluble salts and the acid,drying the ends and winding the treated, dried ends on individualholders; all with substantially only that tension produced by drawingthe ends through the several chemical treating baths. a

4. The continuous process of treating and finishing a multiplicity ofseparate cotton yarn ends which comprises simultaneously drawing theends through a caustic soda bath of mercerizing strength, then throughsuccessive water baths to remove excess caustic soda but leaving behindthe combined caustic soda, then while still moist through a coppersulphate, ammonia, caustic soda solution-prepared in substantially thefol-.

lowing proportions, copper sulphate 39.31 grams per liter, ammonia 66grams per liter, caustic soda (NaOH) 12.105 grams per liter, and waterto make one liter, whereof the excess copper compensates for the causticsoda carried into said solution by the yarn, the ends being maintainedout of contact with one another in the passage through said solution; bycausing each of them to travel through a capillary channel; then throughan acid bath and through water baths to remove the soluble salts and theacid, drying the ends and winding the treated, dried ends on individualholders.

5. The continuous process of treating and finishing a multiplicity ofsingle cotton yarn ends which comprises the steps of simultaneouslydrawing the ends through a series of successive baths with substantiallyonly that amount of tension produced by drawing the ends through saidbaths, the baths in their order being a caustic soda bath of mercerizingstrength, a series of water baths to progressively remove excess causticsoda, but leaving behind combined caustic soda, a copper, ammonia,caustic soda bath pre- 4 r n pared in substantially the followingproportions; copper sulphate 39.31 grams per liter, ammonia 66 grams perliter, caustic soda (NaOH) 12.105

j caustic soda bath unifiow.

7. The method oi efiectively subjecting yarn ends to a. liquid treatmentbath which consists in causing the liquid oi' the bath by capillaryaction to rise vertically between closely spaced stationary plates to apoint above the level of the body of the bath and in drawing theyarnthrough that portion 01 the liquid which has been raised above the levelof the bath, the point oi! ingress oi the yarn being above the level oithe body of the bath but below the level oi! the liquid so raised.

8. The method of eflectively subjecting a mul-. tiplicity of yarn endsto a liquid treatment bath which consists in causing by capillary actionthe liquid in the bath to rise vertically between closely spacedstationary plates at a plurality of spaced points above the level of thebath and in drawing a yarn end through each such raised portion ofliquid, the point of ingress of each end being above the level of theliquid in the bath and below the level of the raised liquid.

WILLIAM H. FURNESS.

